The RenderMan Interface - Paul Bourke

The number of tags is determined implicitly by the length of the tags array, and must
match the value as determined from the nargs array.
EXAMPLE
SubdivisionMesh ”catmull-clark” [4 4 4 4 4 4 4 4 4] [ 0 4 5 1 1 5 6 2 2 6 7
3 4 8 9 5 5 9 10 6 6 10 11 7 8 12 13 9 9 13 14 10 10 14 15 11 ]
[”interpolateboundary”] [0 0] [0] [0] ”P” [-60 60 0 -60 20 0 -60
-20 0 -60 -60 0 -20 60 0 -20 20 45 -20 -20 45 -20 -60 0 20 60 0
20 20 45 20 -20 45 20 -60 0 60 60 0 60 20 0 60 -20 0 60 -60 0]
SEE ALSO
RiPointsPolygons
5.4 Quadrics
Many common shapes can be modeled with quadrics. Although it is possible to convert
quadrics to patches, they are defined as primitives because special-purpose rendering programs
render them directly and because their surface parameters are not necessarily preserved
if they are converted to patches. Quadric primitives are particularly useful in solid
and molecular modeling applications.
All the following quadrics are rotationally symmetric about the z axis (see Figure 5.3). In all
the quadrics u and v are assumed to run from 0 to 1. These primitives all define a bounded
region on a quadric surface. It is not possible to define infinite quadrics. Note that each
quadric is defined relative to the origin of the object coordinate system. To position them at
another point or with their symmetry axis in another direction requires the use a modeling
transformation. The geometric normal to the surface points “outward” from the z-axis, if
the current orientation matches the orientation of the current transformation and “inward” if
they don’t match. The sense of a quadric can be reversed by giving negative parameters.
For example, giving a negative thetamax parameter in any of the following definitions will
turn the quadric inside-out.
Each quadric has a parameterlist. This is a list of token-array pairs where each token is one
of the standard geometric primitive variables or a variable which has been defined with
RiDeclare. For all quadrics, primitive variables of class constant and uniform must supply
a single data element of the appropriate type. Primitive variables that are varying or vertex
must supply 4 data values, which will be interpolated bilinearly across the quadric surface.
Position variables should not be given with quadrics. All angular arguments to these functions
are given in degrees. The trigonometric functions used in their definitions are assumed
to also accept angles in degrees.
RiSphere ( RtFloat radius, RtFloat zmin, RtFloat zmax, RtFloat thetamax, ...parameterlist...)
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